Enhanced\nPerformance and Stability of Perovskite Solar\nCells Through Surface Modification with Benzocaine Hydrochloride

Current\ndevelopment of inverted p-i-n perovskite solar cells (PSCs),\nwith nickel oxide as the hole transport layer, is progressing toward\nlower net costs, higher efficiencies, and superior stabilities. Unfortunately,\nthe high density of defect-based traps on the surface of perovskite\nfilms significantly limits the photoelectric conversion efficiency\nand operational stability of perovskite solar cells. Finding cost-effective\ninterface modifiers is crucial for the further commercial development\nof p-i-n PSCs. In the present work, we report a passivation strategy\nusing a multifunctional molecule, benzocaine hydrochloride (BHC),\nwhich is shown to reduce defect density and enhance the photovoltaic\nperformance and stability of the resultant p-i-n PSCs. It has been\nrevealed that BHC strongly interacts with perovskite precursor components\nand triggers the evolution of the perovskite absorber film morphology\nand enables improved surface energy level alignment, thus promoting\ncharge carrier transport and extraction. These properties are beneficial\nfor improving open-circuit voltage (<i>V<sub>OC</sub></i>) and fill factor (FF). Our results show that the photoelectric conversion\nefficiency (PCE) of p-i-n PSCs with nickel oxide as the hole transport\nlayer increased from an initial 20.0% to 22.1% after being passivated\nwith BHC, and these passivated devices also exhibited improved stability.\nDFT calculations reveal the unusual ability of the BHC passivant to\nimprove band alignment while also preventing the accumulation of holes\nat the interface. In this work, the advantages of BHC passivation\nare demonstrated by linking theoretical calculations with optical\nand electrical characterizations.